OLDEST AND LOWEST LATITUDINAL OCCURRENCE OF PALAEOAPLYSINA - MIDDLE PENNSYLVANIAN ELY LIMESTONE, BURBANK HILLS, UTAH

A primitive variety of Palaeoaplysina laminaeformis Krotov is the prim ary biotic constituent of a two-meter-thick biostrome in the upper fly Limestone of western Utah. Associated fusulinaceans and stromatoporoi ds indicate an early Desmoinesian (Middle Pennsylvanian) age, making i t the oldest documented occurrence of non-ancestral Palaeoaplysina in the world. Plate-supported packstone with 40-60% interstitial peloidal mud and silt-size fossil debris constitutes the dominant biostrome ro ck fabric. During the Late Carboniferous, non-ancestral palaeoaplysini ds were restricted to the fly and Sublett basins of Utah and Idaho, re spectively. By Early Permian time, however, they played a significant role in, the construction. of reefs and biostromes across the entire n orthern margin of Laurussia.